SELECTIVE-INHIBITION BY ALCOHOL AND CORTISOL OF NATURAL-KILLER-CELL ACTIVITY OF LYMPHOCYTES FROM CORD-BLOOD

1. The immunosuppressive effects of drugs such as alcohol or hormones such as cortisol may be age-related. To test this hypothesis, the auth ors investigated the in vitro effects of ethanol (EtOH) and cortisol o n Natural Killer (NK) cell activity of lymphocytes from normal cord bl ood in comparison with that of lymphocytes from normal adult periphera l blood. 2. K562, an erythroleukemia cell line, was used as a target i n a 4 hr Cr-51 release assay. 3. Ethanol at 0.3% (V/V) and cortisol at 0.05, 0.1 and 0.2 mu g/ml concentrations, added directly to a mixture of effector and target cells significantly suppressed the NK activity of cord blood lymphocytes in a dose dependent fashion, whereas simila r concentrations of either EtOH or cortisol did not manifest significa nt immunoregulatory effects on NK cell activity of normal adult lympho cytes. 4. Pre-treatment of the target with either EtOH or cortisol for 4 hours did not affect cytotoxicity. Inhibition of cytotoxicity was a lso not due to direct toxicity of effector cells because lymphocytes t reated with either EtOH or cortisol showed normal Cr-51 release and th eir viability was comparable to that of untreated control cells. 5. Th is suggests a selective inhibitory effect of EtOH and cortisol on NK a ctivity of neonatal lymphocytes that may be of clinical significance.